Elad, Y., Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
Zvieli, Y., Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
Chet, I., Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel

Four isolates of Trichoderma harzianum Rifai inhibited linear growth and microsclerotia production in Macrophomina phaseolina in vitro. The antagonist proliferated in dual liquid culture with M. phaseolina and significantly decreased the number of its viable propagules. Peat bran preparation of T. harzianum reduced disease incidence, in greenhouse-planted beans, by 37-74%. Coating melon seeds with T. harzianum conidia reduced disease incidence by 37·5-46·3%. In vitro growth of T. harzianum was affected less than that of the pathogen by applications of pentachloronitrobenzene or dazomet. The biocontrol agent was as effective as the chemicals, and combining the two under greenhouse conditions slightly enhanced disease control. In the field, charcoal root rot of melons and corn was reduced by 22% and 28%, respectively. Moreover, T. harzianum treatments in melons resulted in an earlier development of fruit. © 1986.